This goes for almost any obnoxious behavior on the internet. It's about 5-10% of people who are just assholes (of whatever description), and everyone else is fine. It only seems like the whole place is jerks because of how noisy the jerks are, and how skilled they are at amping up the normal people into noisy arguments that go nowhere.
Any time you're in one of those comments sections, take a step back and look at the number of people who are actually initiating the dickishness and you'll see that it's a tiny tiny minority.